System for measuring energy using digitally controlled welding power sources

ABSTRACT

A method and system for internally determining, within a welding power supply, the energy input into a weld during a welding operation. The method includes determining a total energy input into the weld during a first time period, and determining a length of the weld made during the first time period.

REFERENCE TO RELATED APPLICATIONS/INCORPORATION BY REFERENCE

This patent application is a continuation-in-part (CIP) of U.S. patentapplication Ser. No. 11/566,719 filed on Dec. 5, 2006.

BACKGROUND OF THE INVENTION

1. Field of the Invention

Devices, systems, and methods consistent with the invention relate to ameasurement of energy imparted to a weld.

2. Description of the Related Art

The mechanical properties of a weld are related in part to the amount ofenergy input to the weld and the cooling rate of the workpiece material.If the amount of energy input to a weld is known, this value may be usedin conjunction with the known cooling rate of the workpiece material todetermine the mechanical properties of the weld for quality controlpurposes.

The amount of energy input to a weld is directly related to the voltage(V) and current (I) used to create the weld. In older related artsystems voltage and current values do not widely vary during weldingoperations. Thus, in these systems, the amount of energy input into aweld may be measured using average voltage and current values, or RMSvoltage and current values.

Unfortunately, many current welding processes have relatively complexoutput characteristics, which cause voltage (V) and current (I) valuesto be widely varied during welding operations. For these systems,averages or RMS determinations of voltage and current values are nolonger acceptably accurate for determining the amount of energy input towelds. Accordingly, an accurate, simple and effective measurement ofenergy input to a particular weld is desired.

BRIEF SUMMARY OF THE INVENTION

The invention provides an accurate, simple and effective measurement ofenergy input.

According to an aspect of the invention, a method for monitoring awelding operation within a welding power supply is provided, the methodincluding: determining a total energy input into a weld during a firsttime period; determining a length of the weld made during the first timeperiod; and determining an energy input per unit length during the firsttime period using the determined total energy input and the determinedlength of the weld.

According to another aspect of the invention, a welding power supplyconfigured to monitor a welding operation is provided, the power supplyincluding: a first determiner to determine a total energy input into aweld during a first time period; a second determiner to determine alength of the weld made during the first time period; and a thirddeterminer to determine the energy input per unit length during thefirst time period using the determined total energy input and thedetermined length of the weld.

According to another aspect of the invention, a method for monitoring awelding operation within a welding power supply is provided, the methodincluding: determining a total energy input into a weld during a firsttime period; determining a change in a physical characteristic of awelding consumable used in the welding operation during the first timeperiod; and determining an energy input per physical characteristic ofthe welding consumable during the first time period using the determinedtotal energy input and the determined change in the physicalcharacteristic of the welding consumable.

According to another aspect of the invention, a welding power supplyconfigured to monitor a welding operation is provided, the welding powersupply including: a first determiner to determine a total energy inputinto a weld during a first time period; a second determiner to determinea change in a physical characteristic of a welding consumable used inthe welding operation during the first time period; and a thirddeterminer to determine an energy input per physical characteristic ofthe welding consumable during the first time period using the determinedtotal energy input and the determined change in the physicalcharacteristic of the welding consumable.

According to another aspect of the invention, a method for monitoring awelding operation within a welding power supply is provided, the methodincluding: sampling pairs of instantaneous voltage and current valuesfrom a welding waveform during a first time period; determininginstantaneous energy values from the sampled pairs of instantaneousvoltage and current values; and summing the instantaneous energy valuesto determine a total energy input into a weld during the first timeperiod.

According to another aspect of the invention, a welding power supplyconfigured to monitor a welding operation is provided, the welding powersupply including: a sampler to sample pairs of instantaneous voltage andcurrent values from a welding waveform during a first time period; afirst determiner to determine instantaneous energy values from thesampled pairs of instantaneous voltage and current values; a summer tosum the instantaneous energy values; and a second determiner todetermine a total energy input into a weld during the first time period.

According to another aspect of the invention, a method for monitoring ahybrid welding operation is provided, the method including: determiningan energy input into a weld by a first welding process during a firsttime period; determining an energy input into the weld by a secondwelding process during the first time period; determining a total energyinput into the weld during the first time period by adding the energyinput into the weld by the first welding process and the energy inputinto the weld by the second welding process; determining a length of theweld made during the first time period; and determining an energy inputper unit length during the first time period using the determined totalenergy input and the determined length of the weld.

According to another aspect of the invention, a hybrid welding system isprovided, the hybrid welding system including: a first determiner todetermine an energy input into a weld by a first welding process duringa first time period; a second determiner to determine an energy inputinto the weld by a second welding process during the first time period;a third determiner to determine a total energy input into the weldduring the first time period by adding the energy input into the weld bythe first welding process and the energy input into the weld by thesecond welding process; a fourth determiner to determine a length of theweld made during the first time period; and a fifth determiner todetermine the energy input per unit length during the first time periodusing the determined total energy input and the determined length of theweld.

The above stated object as well as other objects, features andadvantages of the invention will become clear to those skilled in theart upon review of the following description.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and/or other aspects of the invention will be more apparent bydescribing in detail exemplary embodiments of the invention withreference to the accompanying drawings, in which:

FIG. 1 is a diagram of a welding system according to an exemplaryembodiment of the invention;

FIG. 2 shows an exemplary embodiment of a display according to anexemplary embodiment of the invention;

FIG. 3 is a diagram of a voltage and current measurement strategyaccording to an exemplary embodiment of the invention;

FIG. 4 is a diagram of a energy determination strategy according to anexemplary embodiment of the invention;

FIG. 5 is a diagram of a method of energy determination according to anexemplary embodiment of the invention;

FIG. 6 is a diagram of another method of determining energy according toan exemplary embodiment of the invention;

FIG. 7 is a diagram of a system for measuring energy according to anexemplary embodiment of the invention; and

FIG. 8 is a diagram of another method of determining energy according toan exemplary embodiment of the invention.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

Exemplary embodiments of the invention will now be described below byreference to the attached Figures. The described exemplary embodimentsare intended to assist the understanding of the invention, and are notintended to limit the scope of the invention in any way. Like referencenumerals refer to like elements throughout.

FIG. 1 is a diagram of a welding system according to an exemplaryembodiment of the invention. The welding system 100 includes a weldingpower source 110, which generates output welding waveforms for weldingoperations. The welding power source 110 can be constructed in anyappropriate manner.

The welding system 100 also includes a display 115 and a user interface116. Display 115 is capable of displaying information in any suitablemedium (e.g., for the operator to monitor), and is operationallyconnected to the welding power source 110 (e.g., by a wired or wirelessconnection). Alternatively, the display 115 may be an integral part ofthe welding power source 110. User interface 116 is capable of acceptinginformation (e.g., from the operator), and is operationally connected tothe welding power source 110 (e.g., by a wired or wireless connection).Alternatively, the user interface 116 may be an integral part of thewelding power source 110. As a further alternative, display 115 and/oruser interface 116 may be a portable electronic device (e.g., a laptop,PDA or smart-phone) that is operatively connected (e.g., by a wired orwireless connection) to the welding system 100.

An exemplary embodiment of a combination display 115/user interface 116is shown in FIG. 2. This embodiment shows a digital display and variousdata entry controls and ports. Any number of suitable combinations ofdisplays, controls and/or ports may be alternatively used, includingvirtual controls.

The welding system 100 further includes a welding cable 120, a weldingtool 130, a workpiece connector 150, a wire supply 160, a wire feeder170, a wire 180, and a workpiece 140. Welding tool 130 may be controlledto form a weld in any appropriate manner (e.g., manually, automatically,or semi-automatically). In this embodiment, welding tool 130 is awelding gun, but may also be a welding torch or consumable, depending onthe welding process utilized.

In welding system 100, the wire 180 is fed into the welding tool 130from the wire supply 160 via the wire feeder 170. In this embodiment,wire supply 160 is illustrated as a spool, but any appropriate wiresupply strategy may be used, such as coiled or boxed wire supplies. Inother embodiments, a welding torch may be used with separate electrodes(e.g., such as used in a stick welding process), and welding system 100would not require the wire supply 160, the wire feeder 170, or the wire180.

In welding system 100, the welding cable 120 is a single coaxial cableassembly, but any appropriate single- or multi-cable construction may beutilized. For example, the welding cable 120 may include a first cablelength running from the welding power source 110 to the welding tool130, and a second cable length running from the workpiece connector 150to the welding power source 110.

In welding system 100, a welding output circuit path 105 runs from thewelding power source 110 through the: welding cable 120; welding tool130 (including the distal tip of wire 180); arc 190; workpiece 140;workpiece connector 150, and back through the welding cable 120 to thewelding power source 110. Other appropriate welding output circuit pathsexist for the alternative welding systems 100 discussed above. In FIG.1, during welding operations, electrical current runs through thewelding output circuit path 105 as a voltage is applied in response toan output welding waveform created by welding power source 110. Arc 190is thereby formed between the welding tool 130/wire 180 and theworkpiece 140. Arc 190 inputs energy into the workpiece 140 to form aweld.

As discussed above, the amount of energy input into the weld directlyaffects the physical properties of the resultant weld. In order toprovide an accurate, simple and effective measurement of energy input bycomplex waveforms, it was determined by the inventors that the complexwaveforms could be parsed into discrete sampling intervals, and, foreach sampling interval, the instantaneous voltage and current could berecorded. Then, the product of the recorded voltage and current for eachsampling interval could be summed, and this summed number could then beutilized to provide a more accurate representation of the energy inputinto a weld.

FIG. 3 illustrates an exemplary embodiment of an operation where aninstantaneous voltage and current is measured during a samplinginterval. In FIG. 3, measurement 300 of an output welding waveform'svoltage 320 and current 330 over a sufficiently small sampling time 310is performed. The duration of the sampling time 310 can be anyappropriate time period, but should be set depending on the frequencycontent of the output welding waveform's voltage and current, and theaccuracy desired. In this regard, the sampling interval should be smallenough (i.e., the sampling rate should be high enough) to properlycharacterize the output welding waveform.

The sampled voltage 320, sampled current 330, and sampling time 310 arethen multiplied to determine an instantaneous energy:

instantaneous energy−V_(i)*I_(i)*Δt;  (1)

This instantaneous energy value may then be integrated with respect tothe output welding waveform over a total time to determine the totalenergy input to the weld during that time. The total time may be the arctime (e.g., the time during which an arc is maintained in making an arcweld), or any other desired time period. The total energy input may alsobe considered to be a sum of the product of multiple sets of sampledvoltages and currents, and the total time, and can therefore berepresented as:

energy input over time=Σ(V _(i) *I _(i))_(n) *Δt _(t)  (2)

where N is the number of voltage and current sample pairs over thesuitable time period.

Alternatively, or in addition, the true instantaneous power may bedetermined by multiplying the sampled voltage 320 and the sampledcurrent 330, when the sampling time 310 is sufficiently small.

instantaneous power=V _(i) *I _(i)  (3)

The true power input may be considered to be a sum of the products ofmultiple sets of sampled voltages and currents, divided by the number ofsets of sampled voltages and currents, and can therefore be representedas:

true power input=[Σ(V _(i) *I _(i))_(n) ]/N  (4)

where N is the number of voltage and current sample pairs over thesuitable time period.

In this embodiment, the power source 110 is capable of performing themeasurement of the instantaneous voltage and current, the determinationof equations (1)-(4), and any other associated measurement, storage anddetermination operations. Power source 110 may be constructed in anyappropriate manner to perform each of these functions, and may includespecialized circuitry to provide the requisite functionality.

The sampling of voltage and current is performed by the power source 110to ensure that complex waveforms are sampled at a high enough rate toallow accurate determination of total energy (and/or true power). Thisallows the sampled values to be multiplied together along with thesampling interval to determine multiple instantaneous energy samplesthat may be integrated or summed over a predefined total time (e.g., thearc time or other defined time period) to determine total energy inputinto the weld, not just an average energy. Further, because the variousdeterminations are performed by power source 110, the sampled voltageand current values do not have to be transferred out of the power sourcethrough connections that may ultimately slow the determinations. Powersource 110 may sample voltage and current values via any suitablesampling method, such as by use of an electrical measuring circuitcapable of high speed sampling of the output welding waveform, andanalog-to-digital conversion of the sampled values.

The welding system 100 is also capable of providing for the display ofone or more of the instantaneous energy, instantaneous power, trueenergy, and true power to the operator of the welding equipment invarious ways. For example, the values may be visually presented ondisplay 115 for an operator's review. Alternatively, the information maybe displayed on a portable electronic device (e.g., a laptop, PDA orsmart-phone) that is operatively connected (e.g., by a wired or wirelessconnection) to the welding system 100. Alternatively, or additionally,the information could be audibly indicated. The values may also betransmitted over a network connection to allow central review of thewelding operation by a supervisor, such as a quality control engineer orshift supervisor.

In this embodiment, processing of and/or determinations using thesampled voltage and current is performed in real time within the powersource 110 via any suitable processing and determination method. Forexample, the processing and/or determinations may be performed by aprocessor such as a digital signal processor or a software-controlledprocessor, and/or via a look-up table such as a programmed EEPROM memorybeing addressed by the sampled voltage and current values to yieldinstantaneous energy values.

FIGS. 4A and 4B illustrate in more detail an exemplary method of energydetermination according to the invention. Method 400 determines theenergy 420 input to a weld via a welding operation (e.g., using thewelding system of FIG. 1). FIG. 4A illustrates an exemplary weldingoutput waveform 410 with voltage 430 and current 450 over an arc time480. According to the process described above, pairs of instantaneousvoltage levels and instantaneous current levels are sampled from voltage430 and current 450. Using these sampled values, instantaneous energyvalues 460 and/or instantaneous power values 470 may be determined, asshown in FIG. 4B. The instantaneous energy values 460 then may beintegrated or summed over the arc time 480 to determine the total energyvalue 490 input to the weld over the arc time 480. As can also be seenin FIG. 4B, the cumulative total energy 420 at any subset of the arctime 480 may be determined, and increases over time as energy is inputto the weld via the arc 190 during an arc welding operation. When theweld is complete at the end of the arc time 480, the final total energy490 is known. Any of this sampled or determined data may be displayed bythe welding system 100 via display 115 or portable device, as discussedabove.

Because the cumulative total energy 420 at any point and the totalenergy 490 at the end of the arc time 480 are known, either or both ofthese values may be compared to known standards of acceptability todetermine whether or not the quality of the weld is acceptable. Thiscomparison may be performed by the operator of the welding system 100,using displayed energy values and a reference that indicates thetolerances for the particular material or materials being welded.Alternatively, the welding system 110 may automatically determine if theweld is acceptable by comparing the cumulative total energy 420 and/ortotal energy 490 to standards regarding the material or materials beingwelded. In this regard, the standards may be input and/or stored in thewelding system 100 by any suitable method. For example, the standardsmay be input via user interface 116 and/or another portable device.Alternatively, the standards may be accessible to the welding system 100by network connection based on a determination of the type of materialor materials being welded. The type of material may be input by theoperator of the welding system, or automatically determined by thewelding system via bar code, RFID, material sensors, or the like.

If the value of total true energy falls outside the standards, thewelding system 100 may take action, such as alerting the operator via avisual or audible warning, halting welding operations, logging an event,or any other appropriate action. As a result, the operator can haveconfidence that the welding operation is proceeding within acceptableparameters.

Additionally, a total energy per unit length of the weld may bedetermined and displayed for the operator. In this regard, the totalenergy may be measured for a particular time interval (e.g., the arctime or subset thereof), and divided by the length of the weld duringthat particular time interval. The total energy may thus be presented astotal energy per unit length (e.g., kJ/inch or kJ/mm). Similarly, apower per unit length may be determined and displayed for the operatorby determining a power input level for a particular time interval, anddividing that value by a distance traveled by the welding tool 130during the particular time interval. The power may this be presented aspower per unit length (e.g., watts/inch or watts/mm).

The total length of the weld may be determined by any suitable method.For example, in manual systems, an operator may measure the weld, andinput the length into the welding system 100. Alternatively, the weldingsystem 100 may include sensors that determine the position of any of thewelding tool 130, workpiece 140 or any other moving part of the weldingsystem related to welding tool 130 and/or workpiece 140. A weldingsystem 100 that includes such sensors can utilize the positioninformation and operational information of the welding process todetermine the total weld length. As a still further example, inautomatic welding systems, the welding tool 130 and/or workpiece 140moves according to computerized control. Thus, the welding system 100may monitor the position and operation of the welding tool 130 and/orworkpiece 140 (or other moving part of the welding system 100) todetermine a weld length.

Additionally, the total length of the weld may be measured indirectly bymonitoring the relative travel speeds of the welding tool 130 and/orworkpiece 140 to each other by any suitable method. For example, anoperator may input the travel speeds into the welding system 100.Alternatively, the welding system 100 may include sensors that determinethe travel speeds of the welding tool 130 and/or workpiece 140. As astill further example, in automatic welding systems, the welding tool130 and/or workpiece 140 moves according to computerized control. Thus,the welding system 100 may monitor the travel speeds of the welding tool130 and/or workpiece 140 (or other moving part of the welding system100) to determine travel speeds. Alternatively, the welding travel speedmay be controlled by some other external device which provides thetravel speed to the welding system 100.

In addition to displaying the true energy per unit length, this valuemay be compared to known standards of acceptability to determine whetheror not the quality of the weld is acceptable. This comparison may beperformed by the operator of the welding system 100, using the displayedenergy per unit length value and a reference that indicates thetolerances for the particular material or materials being welded.Alternatively, the welding system 110 may automatically determine if theweld is acceptable by comparing the total energy per unit length tostandards regarding the material or materials being welded. In thisregard, the standards may be input and/or stored in the welding system100 by any suitable method. For example, the standards may be input viauser interface 116 and/or another portable device. Alternatively, thestandards may be accessible to the welding system 100 by networkconnection based on a determination of the type of material or materialsbeing welded. The type of material may be input by the operator of thewelding system, or automatically determined by the welding system viabar code, RFID, material sensors, or the like.

If the value of total energy per unit length falls outside thestandards, the welding system 100 may take action, such as alerting theoperator via a visual or audible warning, halting welding operations,logging an event, or any other appropriate action. As a result, theoperator can have confidence that the welding operation is proceedingwithin acceptable parameters.

FIGS. 5 and 6 illustrate exemplary methods of determining and displayingenergy input per unit length. FIG. 5 illustrates a method utilizing amanually input weld length, while FIG. 6 illustrates a method utilizingan automatically determined weld length. These methods may be used withthe welding system 100 described above, or with any suitable weldingsystem.

In operation 510 of FIG. 5, corresponding pairs of instantaneousvoltages and instantaneous currents are sampled from a welding outputwaveform. The corresponding pairs of instantaneous voltages andinstantaneous currents are sampled at a particular sampling rate over aparticular arc time. Operation 510 may be performed using any suitablehardware and/or software including, for example, analog-to-digitalsampling devices operating at minimum sampling rates of between 8-10KHz, or other appropriate sampling rates.

In operation 520, instantaneous energy values are determined from thepairs of sampled instantaneous voltages and currents. Each instantaneousenergy value may be determined by determined the product of the samplingtime interval Δt (corresponding to the particular sampling rate), andthe particular instantaneous voltage and current. Alternatively, eachinstantaneous energy value may be determined by addressing a look-uptable with the corresponding current value and voltage value pair withinthe welding power source, and outputting the corresponding instantaneousenergy value. Operation 520 may be performed by any suitable method,such as by a digital signal processor, a processor that executessoftware instructions, or a device (e.g., an EEPROM) or data structure(e.g., database or file) that stores the look up table.

In operation 530, a total energy is determined over the arc time fromthe instantaneous energy values. The total true energy may be determinedby determining the sum of the plurality of instantaneous energy valueswithin the welding power source. Operation 530 may be performed by anysuitable method, such as by a digital signal processor or a processorthat executes software instructions.

In operation 540, a weld length of the resultant weld is measured. Theweld length may be measured in any suitable manner. For example, theweld length may be measured manually by using a manual measuring device(e.g., a calibrated ruler or other manual measuring tool).Alternatively, the weld length may be measured automatically by using anautomatic measuring device (e.g., a laser measuring system which detectsand determines the length of the resultant arc weld) or variouspositional and/or movement sensors in the welding system.

In operation 550, the weld length is input into the welding powersource. The weld length may be input in any suitable manner. Forexample, the weld length may be input by hand via a user interface(e.g., user interface 116 of FIG. 1, or FIG. 2, or another portableelectronic device). The user interface may provide any suitableinterface (e.g., a dial, a touch screen, a keyboard, a mouse to select avalue from a menu, or speech recognition capability) for receiving theweld length. Other user interface means are possible as well, inaccordance with various alternative embodiments.

In operation 560, a value of energy input per unit length is determinedfrom the total energy value and the input weld length value. Todetermine the energy input per unit length, the total energy value maybe divided by the input weld length. Alternatively, the value of energyper unit length may be determined by addressing a look-up table with thetotal energy value and the input weld length within the welding powersource, and outputting the corresponding total energy per unit length.Operation 560 may be performed by a processor that executes softwareinstructions, or a device (e.g, a EEPROM) or data structure (e.g.,database or file) that stores the look-up table.

In operation 560, energy input per unit length may be determined by thefollowing equation:

Energy/Unit Length(J/in)=[Total Energy(Joules)]/[weldlength(inches)]  (5)

or:

Energy/Unit Length(J/mm)=[Total Energy(Joules)]/[weld length(mm)]  (6)

Other formulas for of energy input may be utilized in accordance withvarious embodiments.

In the method illustrated in FIG. 5, the energy per unit length may bedetermined in view of the simple entering of a measured length (e.g, ininches or mm). Because the operator is simply entering the measuredlength, the operator does not have to worry about writing down and thenentering multiple variables having different units, or making manualdeterminations with a calculator, which could lead to human error.

As an alternative to the method illustrated in FIG. 5, operation 550 mayutilize entry of the travel speed of the welding operation rather thanthe total weld distance (as discussed above). This data, in conjunctionwith the measured instantaneous voltage and current, and the measuredtime, can also provide energy input per unit length, according to thefollowing formulas:

$\begin{matrix}{{{Energy}\text{/}{Unit}\mspace{14mu} {Length}\mspace{14mu} ( {J\text{/}{in}} )} = \frac{\lbrack {{Total}\mspace{14mu} {Energy}\mspace{14mu} ({Joules})} \rbrack}{\begin{bmatrix}{{{travel}\mspace{14mu} {speed}\mspace{14mu} ( {{in}\text{/}\min} )} \star} \\{{arc}\mspace{14mu} {time}\mspace{14mu} ( \min )}\end{bmatrix}\mspace{11mu}}} & (7) \\{{{Energy}\text{/}{Unit}\mspace{14mu} {Length}\mspace{14mu} ( {J\text{/}{in}} )} = \frac{\lbrack {{{Total}\mspace{14mu} {Energy}\mspace{14mu} ({Joules})} \star 60} \rbrack}{\begin{bmatrix}{{{travel}\mspace{14mu} {speed}\mspace{14mu} ( {{in}\text{/}\min} )} \star} \\{{arc}\mspace{14mu} {time}\mspace{14mu} ( \sec )}\end{bmatrix}\mspace{11mu}}} & (8) \\{{{Energy}\text{/}{Unit}\mspace{14mu} {Length}\mspace{14mu} ( {J\text{/}{mm}} )} = \frac{\lbrack {{Total}\mspace{14mu} {Energy}\mspace{14mu} ({Joules})} \rbrack}{\begin{bmatrix}{{{travel}\mspace{14mu} {speed}\mspace{14mu} ( {{mm}\text{/}\min} )} \star} \\{{arc}\mspace{14mu} {time}\mspace{14mu} ( \min )}\end{bmatrix}\mspace{11mu}}} & (9) \\{{{Energy}\text{/}{Unit}\mspace{14mu} {Length}\mspace{14mu} ( {J\text{/}{mm}} )} = \frac{\lbrack {{{Total}\mspace{14mu} {Energy}\mspace{14mu} ({Joules})} \star 60} \rbrack}{\begin{bmatrix}{{{travel}\mspace{14mu} {speed}\mspace{14mu} ( {{mm}\text{/}\min} )} \star} \\{{arc}\mspace{14mu} {time}\mspace{14mu} ( \sec )}\end{bmatrix}\mspace{11mu}}} & (10)\end{matrix}$

FIG. 6 illustrates the operations of an automated welding system (e.g.,using a robotic welder). In such a system, the travel speed and/orlength of the weld may be known or automatically determined by thewelding system. Thus, these values do not have to be input by anoperator after the weld is completed. The method of FIG. 6 may beutilized with the welding system 100 discussed above, or any suitablewelding system.

In operation 610, corresponding pairs of instantaneous voltages andinstantaneous currents are sampled from a welding output waveform. Thecorresponding pairs of instantaneous voltages and instantaneous currentsare sampled at a particular sampling rate over a particular arc time.Operation 610 may be performed using any suitable hardware and/orsoftware including, for example, analog-to-digital sampling devicesoperating at minimum sampling rates of between 8-10 KHz, or otherappropriate sampling rates.

In operation 620, instantaneous energy values are determined from thepairs of sampled instantaneous voltages and currents. Each instantaneousenergy value may be determined by determining the product of thesampling time interval Δt (corresponding to the particular samplingrate), and the particular instantaneous voltage and current.Alternatively, each instantaneous energy value may be determined byaddressing a look-up table with the corresponding current value andvoltage value pair within the welding power source, and outputting thecorresponding instantaneous energy value. Operation 620 may be performedby any suitable method, such as by a digital signal processor, aprocessor that executes software instructions, or a device (e.g., anEEPROM) or data structure (e.g., database or file) that stores the lookup table.

In operation 630, a total energy is determined over the arc time fromthe instantaneous energy values. The total true energy may be determinedby determining the sum of the plurality of instantaneous energy valueswithin the welding power source. Operation 530 may be performed by anysuitable method, such as by a digital signal processor or a processorthat executes software instructions.

In operation 640, a weld length of the resultant weld is determined. Theweld length may be determined in any suitable manner. For example, theweld length may be determined by sensors located in the welding systemthat determine the location and movement of the welding tool, workpiece,or any other moving part of the welding system. Alternatively, the weldlength may be determined according to the defined movement of portionsof the welding system according to its programmed welding instructions.

In operation 660, a value of energy input per unit length is determinedfrom the total energy value and the determined weld length value. Todetermine the energy input per unit length, the total energy value maybe divided by the input weld length. Alternatively, the value of energyper unit length may be determined by addressing a look-up table with thetotal energy value and the input weld length within the welding powersource, and outputting the corresponding total energy per unit length.Operation 660 may be performed by a processor that executes softwareinstructions, or a device (e.g, a EEPROM) or data structure (e.g.,database or file) that stores the look-up table. Operation 660 mayutilize formulas (5) and (6) above, or any other suitable formulas.

In the method illustrated in FIG. 6, the energy per unit length may bedetermined in a completely automatic fashion, thereby eliminatingoperator error in any such determination.

As an alternative to the method illustrated in FIG. 6, operation 660 mayutilize the travel speed of the welding operation rather than the totalweld distance (as discussed above). This data, in conjunction with themeasured instantaneous voltage and current, and the measured time, canalso provide energy input per unit length, according to formulas(7)-(10) above. In this regard, welding power source 110 mayautomatically keep track of the arc time 480 of the arc weldingoperation using, for example, a timer device or a counter device withinthe welding power source 110. The weld length may be automaticallydetermined within the welding power source by multiplying the arc timeby a predetermined travel speed of the arc welding operation.Alternatively, the weld length may be automatically determined withinthe welding power source by addressing a look-up table with the arc timeand the predetermined travel speed of the arc welding operation, andoutputting the corresponding weld length value.

In addition to the display and monitoring of the acceptability of thetotal energy and energy per unit length values discussed above, the truepower and power per unit length may also be displayed and monitored in asimilar manner.

In addition to the measurement of energy and/or power per unit length ofthe weld, the welding system 100 may measure any characteristic (e.g.,length, mass, volume) of the welding wire 180 in conjunction with theamount of energy or power used. For example, as shown in FIG. 4B, aparticular welding operation may have total energy 490 input to a weldduring arc time 480. To form the weld, a particular amount of weldingwire 180 is used by the welding system 100. This particular amount ofwelding wire 180 has various characteristics (e.g., length, mass andvolume). The total energy 490 input into the weld may be divided by anyof these characteristics to determine an energy input per unit of theparticular characteristic.

The characteristics of the welding wire 180 may be measured and inputinto the welding system 100 by the operator, or automatically determinedor measured by the welding system 100. For example, the total length ofthe welding wire 180 used can be measured by the operator and input tothe welding system 100 via user interface 116, or could be automaticallydetermined by measuring wire travel speed 180, revolution of feed wheelsin feeder 170, or the like. Other characteristics may be measureddirectly in any suitable manner, or can be extrapolated from measuredvalues. For example, mass may be determined by measurement of the wiresupply 160 at the beginning and end of the arc time 480, or can beextrapolated from measured length values if the wire type is known. Inthis regard, wire data may be input and/or stored in the welding system100 via user interface 116 and/or another portable device.Alternatively, the data may be accessible to the welding system 100 bynetwork connection based on a determination of the type of material ormaterials being welded. The type of material may be input by theoperator of the welding system, or automatically determined by thewelding system via bar code, RFID, material sensors, or the like.

In addition to the arc-based welding system 100 described in FIG. 1,welding system 100 may also be a hybrid welding system. As anon-limiting example, hybrid laser welding has recently gainedpopularity. Hybrid laser welding simultaneously utilizes an arc and alaser beam to form a weld, where the laser provides improved penetrationcharacteristics, with a low additive heat input and small heat-affectedzone. To provide such a system, a laser device would be arranged near(or in conjunction with) welding tool 130 within the welding system 100depicted in FIG. 1. The laser device could then direct a laser toworkpiece 140 in conjunction with arc 190. In order to comprehend theadditional energy input into the weld by the laser, the welding system100 may also be configured to measure, display and monitor the energyinput to the weld via the laser (or other secondary energy source in ahybrid arrangement), and include this energy in the total energy valuediscussed above. This total energy value can then be utilized in thesame manner discussed above—for example, to determine: a total orinstantaneous energy used in the welding operation; an energy per unitlength of the weld; or an energy per unit length of a characteristic ofwelding wire 180.

FIG. 7 illustrates an exemplary embodiment of a welding system 700. Thissystem 700 may be used in conjunction with that shown in FIG. 1, or inany other suitable welding system, and may be utilized to perform any ofthe methods discussed herein. FIG. 8 illustrates an exemplary methodutilizing the system shown in FIG. 7.

In welding system 700, output wave shape generator 705 forms the outputwelding waveforms utilized during welding (e.g. the waveform shown inFIG. 4A), in conjunction with control frequency clock 710 and weldtiming control 715. Control frequency clock 710 provides constant timingoutput, while weld timing control 715 defines the beginning and end ofthe welding operations via welding operation indicator 720. Weldingoperation indicator 720 can be any type of module that indicates whetherwelding operations are being conducted, such as a sensor on a weldinggun trigger, or a flag in robotic commands that is activated whenwelding commences. Output power amplifier 725 amplifies the wave shapesgenerated by output wave shape generator 705 into repeating current (I)and voltage (V) waveforms useful for welding operations. As discussedabove, these waveforms may be parsed into discrete sampling periods. Foreach sampling period, total sample summer 735 updates the cumulativenumber of sample periods (and/or sample time) since the weldingoperation indicator 715 indicated the beginning of the current weldingoperation, V, I sampler 727 samples the voltage (V) and current (I)levels output by amplifier 725, V*I determiner 730 determines the V*Ivalue, and V*I summer 740 sums the determined V*I value from V*Ideterminer 730 with each of the determined V*I values from all previoussampling periods of the current operation. The values from summers 735and 740, along with the time for each cycle, are then used by totalenergy determiner 745 to determine the total cumulative energy (e.g.,cumulative total energy 420 of FIG. 4B) used during the weldingoperation (i.e., since the welding operation indicator 715 indicated thebeginning of the current welding operation). Total energy determiner 745may also take into account any energy input into the weld by a secondwelding process in a hybrid arrangement with the arc welding process,such as the hybrid laser welding process discussed above. Thisadditional energy is summed by second welding process energy summer 737during the welding operation.

In order to determine the energy input per unit length during thewelding operation, either or both of the travel speed determiner 760 andtravel distance determiner 775 provide speed or distance information toenergy/unit determiner 780, which then determines an energy per unitlength value (as discussed above in, e.g., the methods of FIGS. 5 and6). Travel speed determiner 760 may obtain travel speed informationeither from a set travel speed 755 or measured travel speed 750. Settravel speed is the speed of travel set by the welding operator orautomatic welding system, while measured travel speed is measured by asensor of any suitable variety. Travel distance determiner 775 mayobtain travel distance either from a set distance 770 or measureddistance 765. Set distance is a distance set by the welding operator orautomatic welding system, while measured distance is a distance measuredmanually by the operator, or automatically by the welding system.Energy/unit determiner 780 then uses the information output from totalenergy determiner 745 and travel speed determiner 760 and/or traveldistance determiner 775 to determine the amount of energy input to aweld per unit length during the welding operation, according to any ofthe equations (5)-(10) discussed above, or any other suitablealternative equations.

Any of the information determined in total energy determiner 745 and/orenergy/unit determiner (or any other related information) may bereported on operator interface 785 (e.g. display 115 and/or userinterface 116 of FIG. 1), or via any other suitable medium usable withwelding system 700. The information may be used by the operator, qualitycontrol personnel, management, or the like to ensure a high-qualityoperation, as discussed in detail above.

As discussed above, welding system 700 may also measure anycharacteristic (e.g., length, mass, volume) of the welding consumable180 in conjunction with the amount of energy or power used. Consumable Adeterminer 777 is provided to monitor and determine the change in thephysical characteristic of the welding consumable. Energy/unitdeterminer 780 then uses the information output from total energydeterminer 745 and consumable A determiner 777 to determine the amountof energy input per physical characteristic of the welding consumable,similarly to that discussed above for the welding wire.

Additionally, comparer/alerter 783 is provided to compare any of thesampled or determined values in system 100 to any normal or desiredoperating ranges for that particular value, and to provide an alert ifthe values fall outside of the normal or desired operating range.Comparer/alerter 783 may provide its comparisons or alerts throughoperator interface 785, or any other appropriate reporting, monitoringor alerting system.

Although several elements of welding system 700 are depicted inschematic form in FIG. 7, the arrangement of these elements is notlimited. The elements may be freely combined or further divided asappropriate to provide the inventive functionality.

FIG. 8 illustrates a method of determining energy input to a weld,and/or energy input per unit length to a weld, in accordance with thesystem illustrated in FIG. 7, and with any of the systems disclosedherein. The method begins at operation 800, when weld timing control 715determines that welding operations have begun via an indication bywelding operation indicator 720. The method then clears any previousdata from total sample/total time summer 735 (operation 805) and V*Isummer 740 (operation 810), the functions of which are described above.At the beginning of each sample period (operation 815), the totalsample/total time summer 735 updates the number of sample periods thathave been measured during the current welding operation (operation 820),the V,I sampler 727 samples voltage (V) and current (I) (operation 825)and the V*I determiner 730 determines V*I for that sample period(operation 830). V*I Summer 740 then adds the V*I value for that sampleperiod to a sum of V*I values for each previous sample period of thewelding operation (operation 835). Operations 820, 825, 830 and 835 maybe repeated until the end of the welding operations. Total energydeterminer 745 may determine a total cumulative energy input into theweld by taking into account the total V*I from V*I summer 740 and thetotal sample periods (or total time) from total sample/total time summer735 (operation 840). Total energy determiner 745 may also take intoaccount any energy input into the weld by a second welding process in ahybrid welding arrangement, as reported by second welding process energysummer 737.

The total weld length, or the weld speed, is then determined usingtravel distance determiner 775 or travel speed determiner 760 (operation845). These values are then used (either solely or in combination) inconjunction with the total energy determined by total energy determiner745 to determine an energy per unit length (operation 850). Lastly, thetotal energy and/or energy per unit length may be reported on operatorinterface, or otherwise reported in welding system 700 (operation 855),in the manner discussed above.

Alternatively, as discussed above, welding system 700 may also determinethe amount of energy input per physical characteristic of the weldingconsumable. In such an arrangement, the change in the physicalcharacteristic of the welding consumable is determined by consumable Δdeterminer 777 (operation 845). This value is then used in conjunctionwith the total energy determined by total energy determiner 745 todetermine the amount of energy input per physical characteristic of thewelding consumable (operation 850). Lastly, the energy input perphysical characteristic may be reported on operator interface, orotherwise reported in welding system 700 (operation 855), in the mannerdiscussed above.

By using this invention, the total energy input to a weld can be moreaccurately determined because the voltage and current are sampled: (1)in the correct phase relative to each other; (2) at a frequencynecessarily greater than that of the output frequency being produced;and (3) over the exact number of sample periods during which the weldingoutput is on. Further, this invention provides an accurate measurementof the energy input into a particular weld without requiring the use ofexpensive external measurement devices.

While the invention has been particularly shown and described withreference to exemplary embodiments thereof, the invention is not limitedto these embodiments. It will be understood by those of ordinary skillin the art that various changes in form and details may be made thereinwithout departing from the spirit and scope of the invention as definedby the following claims.

1. A method for monitoring a welding operation within a welding powersupply, comprising: determining a total energy input into a weld duringa first time period; determining a length of the weld made during thefirst time period; and determining an energy input per unit lengthduring the first time period using the determined total energy input andthe determined length of the weld.
 2. The method of claim 1, furthercomprising reporting the determined energy input per unit length.
 3. Themethod of claim 1, further comprising comparing the determined energyinput per unit length to an acceptable range of energy input per unitlength values for the welding operation.
 4. The method of claim 3,further comprising issuing an alert when the energy input per unitlength is outside of the acceptable range of energy input per unitlength values.
 5. The method of claim 1, wherein determining the totalenergy input into the weld during the first time period comprises:determining a first total energy input into the weld during the firsttime period by a first welding process; determining a second totalenergy input into the weld during the first time period by a secondwelding process; and summing the first total energy and second totalenergy.
 6. A welding power supply configured to monitor a weldingoperation, comprising: a first determiner to determine a total energyinput into a weld during a first time period; a second determiner todetermine a length of the weld made during the first time period; and athird determiner to determine the energy input per unit length duringthe first time period using the determined total energy input and thedetermined length of the weld.
 7. The welding power supply of claim 6,further comprising a reporter to report the determined energy input perunit length.
 8. The welding power supply of claim 6, further comprisinga comparer to compare the determined energy input per unit length to anacceptable range of energy input per unit length values for the weldingoperation.
 9. The welding power supply of claim 8, further comprising analerter to issue an alert when the energy input per unit length isoutside of the acceptable range of energy input per unit length values.10. The welding power supply of claim 5, wherein the first determinerdetermines the total energy input into the weld during the first timeperiod by adding a first total energy input into the weld during thefirst time period by a first welding process and a second total energyinput into the weld during the first time period by a second weldingprocess.
 11. A method for monitoring a welding operation within awelding power supply, comprising: determining a total energy input intoa weld during a first time period; determining a change in a physicalcharacteristic of a welding consumable used in the welding operationduring the first time period; and determining an energy input perphysical characteristic of the welding consumable during the first timeperiod using the determined total energy input and the determined changein the physical characteristic of the welding consumable.
 12. The methodof claim 11, further comprising reporting the determined energy inputper physical characteristic of the welding consumable.
 13. The method ofclaim 11, further comprising comparing the determined energy input perphysical characteristic of the welding consumable to an acceptable rangeof energy input per physical characteristic of the welding consumablevalues for the welding operation.
 14. The method of claim 13, furthercomprising issuing an alert when the energy input per physicalcharacteristic of the welding consumable is outside of the acceptablerange of energy input per physical characteristic of the weldingconsumable values.
 15. The method of claim 11, wherein determining thetotal energy input into the weld during the first time period comprises:determining a first total energy input into the weld during the firsttime period by a first welding process; determining a second totalenergy input into the weld during the first time period by a secondwelding process; and adding the first total energy and second totalenergy.
 16. A welding power supply configured to monitor a weldingoperation, comprising: a first determiner to determine a total energyinput into a weld during a first time period; a second determiner todetermine a change in a physical characteristic of a welding consumableused in the welding operation during the first time period; and a thirddeterminer to determine an energy input per physical characteristic ofthe welding consumable during the first time period using the determinedtotal energy input and the determined change in the physicalcharacteristic of the welding consumable.
 17. The welding power supplyof claim 16, further comprising a reporter to report the determinedenergy input per physical characteristic of the welding consumable. 18.The welding power supply of claim 16, further comprising a comparer tocompare the determined energy input per physical characteristic of thewelding consumable to an acceptable range of energy input per physicalcharacteristic of the welding consumable values for the weldingoperation.
 19. The welding power supply of claim 18, further comprisingan alerter to issue an alert when the energy input per physicalcharacteristic of the welding consumable is outside of the acceptablerange of energy input per physical characteristic of the weldingconsumable values.
 20. The welding power supply of claim 16, wherein thefirst determiner determines the total energy input into the weld duringthe first time period by adding a first total energy input into the weldduring the first time period by a first welding process and a secondtotal energy input into the weld during the first time period by asecond welding process.
 21. A method for monitoring a welding operationwithin a welding power supply, comprising: sampling pairs ofinstantaneous voltage and current values from a welding waveform duringa first time period; determining instantaneous energy values from thesampled pairs of instantaneous voltage and current values; and summingthe instantaneous energy values to determine a total energy input into aweld during the first time period.
 22. The method of claim 21, furthercomprising reporting the determined total energy.
 23. The method ofclaim 21, further comprising comparing the determined total energy to anacceptable range of total energy values for the welding operation. 24.The method of claim 23, further comprising issuing an alert when thetotal energy is outside of the acceptable range of total energy values.25. The method of claim 21, further comprising reporting the determinedinstantaneous energy values.
 26. The method of claim 21, furthercomprising comparing the determined instantaneous energy values to anacceptable range of instantaneous energy values for the weldingoperation.
 27. The method of claim 26, further comprising issuing analert when the determined instantaneous energy value is outside of theacceptable range of instantaneous energy values.
 28. The method of claim21, further comprising: determining a length of the weld made during thefirst time period; and determining the energy input per unit lengthduring the first time period using the determined total energy input andthe determined length of the weld.
 29. The method of claim 28, furthercomprising reporting the determined energy input per unit length. 30.The method of claim 28, further comprising comparing the determinedenergy input per unit length to an acceptable range of energy input perunit length values for the welding operation.
 31. The method of claim30, further comprising issuing an alert when the energy input per unitlength is outside of the acceptable range of energy input per unitlength values.
 32. The method of claim 21, further comprising:determining a change in a physical characteristic of a weldingconsumable used in the welding operation during the first time period;determining the energy input per the physical characteristic of thewelding consumable using the determined total energy input and thedetermined change in the physical characteristic of the weldingconsumable.
 33. The method of claim 32, further comprising reporting thedetermined energy input per physical characteristic of the weldingconsumable.
 34. The method of claim 32, further comprising comparing thedetermined energy input per physical characteristic of the weldingconsumable to an acceptable range of energy input per physicalcharacteristic of the welding consumable values for the weldingoperation.
 35. The method of claim 34, further comprising issuing analert when the energy input per physical characteristic of the weldingconsumable is outside of the acceptable range of energy input perphysical characteristic of the welding consumable values.
 36. A weldingpower supply configured to monitor a welding operation, comprising: asampler to sample pairs of instantaneous voltage and current values froma welding waveform during a first time period; a first determiner todetermine instantaneous energy values from the sampled pairs ofinstantaneous voltage and current values; a summer to sum theinstantaneous energy values; and a second determiner to determine atotal energy input into a weld during the first time period.
 37. Thewelding power supply of claim 36, further comprising a reporter toreport the determined total energy.
 38. The welding power supply ofclaim 36, further comprising a comparer to compare the determined totalenergy to an acceptable range of total energy values for the weldingoperation.
 39. The welding power supply of claim 38, further comprisingan alerter to issue an alert when the total energy is outside of theacceptable range of total energy values.
 40. The welding power supply ofclaim 36, further comprising a reporter to report the determinedinstantaneous energy values.
 41. The welding power supply of claim 36,further comprising a comparer to compare the determined instantaneousenergy values to an acceptable range of instantaneous energy values forthe welding operation.
 42. The welding power supply of claim 41, furthercomprising an alerter to issue an alert when the determinedinstantaneous energy value is outside of the acceptable range ofinstantaneous energy values.
 43. The welding power supply of claim 36,further comprising: a third determiner to determine a length of the weldmade during the first time period; and a fourth determiner to determinethe energy input per unit length during the first time period using thedetermined total energy input and the determined length of the weld. 44.The welding power supply of claim 43, further comprising a reporter toreport the determined energy input per unit length.
 45. The weldingpower supply of claim 43, further comprising a comparer to compare thedetermined energy input per unit length to an acceptable range of energyinput per unit length values for the welding operation.
 46. The weldingpower supply of claim 45, further comprising an alerter to issue analert when the determined energy input per unit length value is outsideof the acceptable range of energy input per unit length values.
 47. Thewelding power supply of claim 36, further comprising: a third determinerto determine a change in a physical characteristic of a weldingconsumable used in the welding operation during the first time period; afourth determiner to determine the energy input per the physicalcharacteristic of the welding consumable using the determined totalenergy input and the determined change in the physical characteristic ofthe welding consumable.
 48. The welding power supply of claim 47,further comprising a reporter to report the determined energy input perphysical characteristic of the welding consumable.
 49. The welding powersupply of claim 47, further comprising a comparer to compare thedetermined energy input per physical characteristic of the weldingconsumable to an acceptable range of energy input per physicalcharacteristic of the welding consumable values for the weldingoperation.
 50. The welding power supply of claim 49, further comprisingan alerter to issue an alert when the energy input per physicalcharacteristic of the welding consumable is outside of the acceptablerange of energy input per physical characteristic of the weldingconsumable values.
 51. A method for monitoring a hybrid weldingoperation, comprising: determining an energy input into a weld by afirst welding process during a first time period; determining an energyinput into the weld by a second welding process during the first timeperiod; determining a total energy input into the weld during the firsttime period by adding the energy input into the weld by the firstwelding process and the energy input into the weld by the second weldingprocess; determining a length of the weld made during the first timeperiod; and determining an energy input per unit length during the firsttime period using the determined total energy input and the determinedlength of the weld.
 52. A hybrid welding system, comprising: a firstdeterminer to determine an energy input into a weld by a first weldingprocess during a first time period; a second determiner to determine anenergy input into the weld by a second welding process during the firsttime period; a third determiner to determine a total energy input intothe weld during the first time period by adding the energy input intothe weld by the first welding process and the energy input into the weldby the second welding process; a fourth determiner to determine a lengthof the weld made during the first time period; and a fifth determiner todetermine the energy input per unit length during the first time periodusing the determined total energy input and the determined length of theweld.